The developmental test team from the 461st Flight Test Squadron at Edwards Air Force Base, Calif., flew an F-35 fitted with Technology Refresh 3 (TR-3) in January, the first flight with the critical upgrade. F-35 Joint Program Office
Photo Caption & Credits

World: Air Power

Jan. 20, 2023

F-35 Flies for the First Time with Tech Refresh 3

By John A. Tirpak


dvances to the F-35 are coming on several fronts. The first F-35A fitted with the Tech Refresh 3 update flew Jan. 6 from Edwards Air Force Base, Calif., the Joint Program Office announced in early January. A new radar is also in the works, according to Northrop Grumman, which builds both the current unit and the more advanced version.

Tech Refresh 3 includes more powerful processors and memory, and is the enabling upgrade on which most of the planned F-35 Block 4 improvements depend. The Block 4 version of the F-35 will have new electronic warfare capabilities, new sensors, and capabilities for new weapons, as well as improved interoperability with both fourth- and fifth-generation fighters.

The Air Force has sought to slow its F-35 purchases in recent years, wishing to wait for the more advanced Block 4 jets, and avoid costly retrofits of older models. But the TR-3 has been delayed by technical problems, driving up F-35 development costs by some $330 million, according to a report from the Government Accountability Office. In April, 2022, the GAO also reported the Block 4 to be three years late. The first production-model F-35 with TR-3—but not the full Block 4 suite—is now scheduled to be included with Lot 15 jets now in early phases of construction. 

Air Force Lt. Gen. Michael Schmidt, program executive officer for the F-35, hailed the first flight of TR-3 as a “significant achievement.” The TR-3, he said in a press release, “is the F-35’s critical computer processing electronics upgrade that will continue to provide all our pilots with the capability they need to be successful against any adversary.” 

The F-35 Joint Program Office said, “The TR-3 program has overcome technical complexity challenges with hardware and software and is now on-track to deliver capability to the U.S. and its allies starting in 2023,” when the first Lot 15 jets will roll off the production line. The government-industry team continues “to find innovative ways to ensure delivery of critical capabilities to defeat future threats. Lessons learned in the execution of the TR-3 program will be applied across the entire Block 4 modernization program.” 

A developmental test team from the 461st Flight Test Squadron conducted the first flight of the TR-3-equipped aircraft at Edwards Air Force Base, Calif. The aircraft was AF-7, one of the Air Force’s designated F-35 test airplanes, instrumented to record actual performance so it can be compared with computer predictions. 

Maj. Ryan Luerson, an Air Force test pilot, flew the 50-minute hop, which reached an altitude of 35,000 feet and a speed just below Mach 1, to test airworthiness and stability of the software. Air Force Lt. Col. Christopher Campbell, commander of the 461st Flight Test Squadron and director of the F-35 Integrated Test Force, said TR-3 “modernizes the computational core of the F-35 air vehicle.” The new TR-3 hardware and software “affect nearly every aircraft feature. Today’s event was just the start of a comprehensive flight test campaign that will both verify and improve the safety, stability, and performance of the whole F-35 weapon system in this new configuration,” he said.

Lockheed Martin aeronautics F-35 Vice President and General Manager Bridget Lauderdale said the flight “is an important step in enabling future capabilities to ensure F-35 remains unrivaled across the globe. We look forward to continued collaboration with the JPO and industry partners to deliver TR-3.”


DOD and prime contractor Lockheed Martin struck a $30 billion production deal for Lots 15 and 16—with options for Lot 17—as 2022 ended. The agreement calls for 145 aircraft in Lot 15, 127 aircraft in Lot 16, and up to 126 in Lot 17, which will include the first jets delivered to Belgium, Finland, and Poland. 

The open-ended Lot 17 allows for 23 more F-35s than the Pentagon originally planned, but when the “handshake deal” on the three lots was announced in July 2022, Pentagon acquisition and sustainment chief William LaPlante said it was “based on” as many as 375 jets. Either way, deliveries are declining—the Lot 12-14 deal, inked in 2019, covered 478 aircraft. The drop aligns with the desire to slow production while waiting for Block 4 to be production-ready. The agreed Lot 15-17 numbers average 132 airplanes per year; well below the 156 per year predicted by Lockheed Martin CEO Jim Taiclet in an investors’ call a year ago. 

In a statement announcing the deal, Schmidt said the deal “strikes the right balance between what’s best for the U.S. taxpayers, the military services, allies, and our foreign military sales customers.” The unit cost of the fighters will average about $75 million a copy, without the Pratt & Whitney F135 engine. With the engine, the last three-lot deal achieved a unit cost below $80 million per jet. The JPO did not provide Air & Space Forces Magazine an all-up cost for the fighters in Lots 15-17.

For the airframe and mission equipment only, the Lot 15-17 cost of F-35s ranges “from $70.2 million to $69.9 million for the F-35A, $80.9 million to $78.3 million for the F-35B, and $90 to $89.3 million for the F-35C,” a Lockheed spokesperson said. Lockheed has been warning for two years that Lot 15 and later lots would cost more due to the greater capability being built into the jet, as well as pandemic-related supply issues and inflation.

Besides TR-3, Block 4 includes some 75 changes, include new or additional weapons, communications and networking upgrades, electronic warfare improvements, cockpit and navigation enhancements, and “radar and [sensor] fusion updates,” a Lockheed spokesperson said. 


Northrop Grumman is building the F-35’s new radar, designated the AN/APG-85, which the company calls the “cornerstone” of the F-35’s future sensor suite. The new unit replaces the AN/APG-81, the active, electronically-scanned array (AESA) radar Northrop builds for today’s F-35s. Although Air Force budget documents have referenced the AN/APG-85 since last year, Northrop hasn’t been allowed to discuss the program until now. 

“The capability of the F-35 advanced radar will enhance the DOD’s ability to execute the National Defense Strategy in the future,” the JPO said in response to an email query from Air & Space Forces Magazine. “Therefore, certain information will continue to be protected by enhanced security measures due to the critical nature of the technology.”

It added, “We do not disclose technical information on operational capabilities.” 

Northrop said the new radar is an “advanced multifunction sensor that will be compatible with all variants of the F-35 aircraft and will be capable of defeating current and projected adversarial air and surface threats.” It’s not yet clear if it will be retrofitted to existing models of the fighter. 

The new radar will probably be available in time to equip seven jets at the tail end of the Lot 17 F-35 contract, with delivery anticipated as soon as late 2025 or early 2026. The AN/APG-85 “will incorporate some of the latest technologies available and help ensure air superiority,” Northrop noted. 

“This advanced sensor will provide unparalleled battlespace situational awareness that translates into platform lethality, effectiveness, and survivability.” Neither Northrop nor the JPO would comment on the degree of commonality between the two radars, or whether the new unit will completely replace the old one or if only certain elements will be changed. 

The current AN/APG-81 can be used to target enemy fighters and ground threats, can track and shoot uncrewed aerial vehicles and cruise missiles, can conduct bomb damage assessment, perform a ground moving target indicator (GMTI) function and provide synthetic aperture radar ground mapping. Presumably, the AN/APG-85 will go beyond those capabilities, with greater resolution and even less susceptibility to jamming and spoofing. 

Government and industry officials have also spoken of the F-35’s future radar being able to conduct electronic warfare, offensive directed energy operations and cyber warfare. 

The new radar will be developed and built at Northrop’s Linthicum, Md., facilities, where the AN/APG-81 is built now. It will be one of the piece of equipment for the Block 4 F-35 many new systems.

The need to provide power and cooling for these new systems is one of the reasons the Air Force is in the throes of deciding what engine will power future F-35s. One option is an all-new engine based on one of the Adaptive Engine Transition Program (AETP) powerplants; the other is an upgrade package of the existing F135 engine, being touted by Pratt & Whitney, which is its sole maker.  

In revealing the new radar, Northrop noted that it’s already a major partner to Lockheed on the F-35, contributing the center fuselage and wing skins, “several sensor systems,” avionics, mission systems and mission-planning software, pilot and maintainer training systems, and “electronic warfare simulation test capability,” in addition to the radar and overall stealth capabilities.                                                                                                 

What Could be Part of the B-21 ‘Family of Systems?’ New Report Offers Insight 

An artist’s illustration depicts an Air Force B-21 Raider escorted on a mission by armed, uncrewed drones. Mike Tsukamoto/staff; Greg Davis/USAF

By Greg Hadley

With the unveiling of the B-21 Raider, speculation and interest in the new bomber have reached a fever pitch, with a first flight still to come in mid-2023.  

But the B-21 won’t just be about the large, flying wing aircraft that rolled out in Palmdale, Calif., on Dec. 2. Air Force officials have frequently spoken about the Raider becoming the lead element of a so-called “family of systems,” and Air Force Secretary Frank Kendall has made defining that family of systems one of his seven “operational imperatives” for the department. 

What exactly will be included in that family remains unknown, but a new research paper from the Mitchell Institute for Aerospace Studies, informed by an unclassified workshop that gathered Air Force leaders, planners, and operators along with industry partners, offers some insight into what might be considered. 

“What we haven’t heard much about is the family of systems that is going to accompany [the B-21]. Just dribs and drabs of information. So this report might actually help … get a handle on some of the capabilities that might be in that family of systems, including weapons, that could help reduce risk and increase the effectiveness of our combat forces,” said retired Col. Mark Gunzinger, the Mitchell Institute’s director of future concepts and capability assessments and a co-author of the paper. 

The three-day workshop, held this summer, was meant in part to develop concepts for what the Air Force calls “autonomous collaborative platforms (ACPS)”—relatively cheap drones that can fly alongside manned aircraft, operating with some level of independence.  

The most high-profile example of these ACPs has been the Air Force’s planned collaborative combat aircraft, intended mainly for fighters. But Caitlin Lee, one of the workshop’s leads and co-author of the  paper, noted that in discussions with the Air Force Research Laboratory, officials have said they envision “a whole family of potential capabilities and a range of different mission sets that this could actually involve.” 

The workshop was aimed at exploring one of those mission sets—the long-range penetrating strike mission that the B-21 will take on. Three teams of experts were tasked with designing up to three kinds of unmanned aircraft to aid the bomber in strikes against an air base, a maritime threat, and a transporter erector launcher in a hypothetical conflict with China in 2030. 

In all three cases, no constraints were put on what kind of aircraft the teams could create, but none of them opted for an “exquisite unmanned fighter” or “exquisite unmanned bomber” that could match the B-21’s range, Lee noted. That’s in line with Kendall’s own comments this past July that the department had determined that a long-range uncrewed escort for the B-21 was cost-prohibitive. 

Instead, the three teams created a mix of UAVs, most with a range of a few thousand miles, a few launched from other bombers. And the capabilities given to each varied as well—some designed to provide defensive counterair; others as intelligence, surveillance, and reconnaissance platforms gathering data; others for suppression of enemy air defenses; and still others as escorts. 

“Two-thirds of the teams design ACPs for counterair, which really speaks to the need for survivability for these penetrating strike packages, where they’re operating in this highly contested air environment,” Lee said. “ … And then ISR was another really important mission. Three of the ACPs had a primary role for that, but I think all ACPs had sensors of some kind or another, because that tracking, especially mobile targets, in contested airspace is a real challenge.” 

Just as notably, the teams sought large quantities of ACPs and were willing to trade off some capability for quantity, Lee noted. 

“If the Air Force is able to buy larger numbers of lower-cost ACPs, that could really drive down risk,” Lee said. “And it’s all about the modest platforms in large numbers versus trying to put more sophisticated capabilities to get that operational advantage.” 

The exact rundown of the intended missions and numbers of drones the teams in the workshop decided on are as follows:

Maritime threat 

  • ACP 1: Defensive counterair, 40 
  • ACP 2: ISR, communications relay, 10 
  • ACP 3: Strike, 20 

Transporter erector launcher

  • ACP 1: Escort, suppression of enemy air defenses, 10 
  • ACP 2: ISR, Suppression of enemy air defenses (SEAD), offensive counterair, 144 (24 per bomber) 
  • ACP 3: ISR, SEAD, offensive counterair, 120 (20 per bomber) 

Air base attack 

  • ACP 1: Escort, 8 
  • ACP 2: SEAD, 16 initially, increased to 32 
  • ACP 3: Jamming, 8 

In all three cases, the workshop experts determined that the addition of these uncrewed teammates reduced risk for the missions. But the authors did note that for the air base attack, in particular, the risk wasn’t driven down as much because the current class of precision-guided munitions require bombers to fly extremely close to targets, assuming a permissive environment. 

“So that is a collateral finding and recommendation from this effort—that the Air Force needs to develop those mid-range weapons that will optimize the strike power and lethality of our penetrating assets,” Gunzinger said. 

Indeed, some of the ACPs designed by the teams in the workshops were essentially loitering munitions—designed to fly above targets and then attack, only to be used once. And as the B-21 continues to develop, new kinds of munitions could very well join that family of systems, too, Lee noted. 

“This family could have all kinds of different capabilities in it, whether it’s space assets, munitions, and potentially ACPs,” Lee said.                                                                                                         

Air Force RC-26 Fleet Heading to the Boneyard

The 141st Operations Group RC-26 sits at Medford Airport in southwest Oregon Sept. 2, 2017. Senior Airman Sean Campbell

By Chris Gordon

The Air National Guard is retiring its entire fleet of 11 RC-26 Condors, the Air Force said Jan. 6. The twin-prop plane had an often under-the-radar, but sometimes controversial role as a reconnaissance aircraft used for both counterdrug and homeland security missions.

A converted civilian airliner, the aircraft attracted unwanted attention several times recently, and for years the Department of Defense has sought to retire the aircraft in favor of cheaper platforms such as drones.

Those efforts had been blocked by advocates on Capitol Hill, most vocally former Rep. Adam Kinzinger (R-Ill.), an RC-26 pilot in the Air National Guard. In both the 2020 and 2021 National Defense Authorization Acts, there were provisions preventing the Air Force from using funds to retire the Condor.

No such provision made it into the 2023 National Defense Authorization Act, though, and  the Air Force said that without a need or funding for the aircraft, the plane will finally be out of service.

“There are no Air Force specific-RC-26B validated requirements nor dedicated funding to support sustainment of the weapons system,” an Air Force spokesperson told Air & Space Forces Magazine.

The Wisconsin Air National Guard concluded operations on Dec. 28, it announced. Representatives for the Air National Guard did not say whether all RC-26 operations have ceased—Alabama, Arizona, California, Iowa, Mississippi, New Mexico, Texas, West Virginia, and Washington all have the aircraft as well.

The Air Force said all 11 RC-26 aircraft will head to the Boneyard at Davis-Monthan Air Force Base, Ariz.

While the Air Force sees no requirements for the RC-26, the Wisconsin National Guard touted the aircraft’s usefulness in its release.

“Officers, civilians, suspects, families and regular citizens who have no idea that the reason that they are alive is because those guys were experts at their jobs, helped chase down and arrest drug dealers, in ways that could not have been done in any other platform,” Lt. Col. Benjamin West, the Wisconsin Air National Guard’s program manager, said in a statement.

“Having spent a large time of my policing career in narcotics work, I can tell you that this mission saves people’s lives,” added Army Col. Paul Felician, director of the Wisconsin National Guard’s counterdrug program. “The stuff that this aircraft enabled law enforcement to do took more drugs off the street and kept people safe from having to go into the direct risk of harm—it’s a sad day to see it go away.”

But the RC-26’s use in law enforcement missions was questionable at times, according to the Air Force’s own accounting. The aircraft monitored protests and relayed information to law enforcement in Minnesota, Arizona, California, and Washington, D.C., after the murder of while George Floyd in police custody in the summer of 2020. Congressional concerns prompted an Air Force Inspector General investigation, which concluded that the National Guard Bureau erred in its deployment of RC-26s in some cases.

The aircraft were directed to fly “overhead imagery Incident Awareness and Assessment (IAA) missions in support of law enforcement and/or National Guard units responding to destruction of property and violence” after Floyd’s murder in 2020, the report said.

“Properly approved missions can support civilian law enforcement, but there is no scenario in which it is acceptable or permissible to use DOD assets to deter demonstrations and protests, assuming they remain lawful,” the report said.

The National Guard Bureau didn’t have “a clear authorization” approved by civilian leaders before RC-26s began flying the missions, according to the IG report, and some of the missions over protests were, in the inspector general’s view, implausibly done for “training” purposes.

Air National Guard leaders have said the platform should be retired because cheaper platforms such as drones could fulfill counternarcotics and homeland security functions. Lt. Gen. Michael A. Loh, Air National Guard director, said the cost to keep RC-26 in the fleet—$30 million per year—could be used to field and invest in newer systems.

“It’s an old aircraft, and there’s current language right now that says I can’t retire that fleet or even expend money to prepare to retire that fleet,” Loh said in 2021. “And so, each year, I’m spending millions of dollars to keep a fleet alive that quite frankly has run its useful life, and I need to actually get out of those to get into something new.

“We’ve actually had better technologies out there to take care of the mission, so even if I needed to do the mission today, I can [do] it with better technologies that are cheaper to operate,” Loh said at the time.